Bike getting very hot?

Question

Hi i when i ride my bike for about 45mins with only stopping a few times at lights my temp sensor goes up to 3/4 and nearly all the way to full. I was wondering what could cause this? i checked my coolant and its nearly full still

by the way its a Yamaha rd125lc

thanks

I just found out that my bike doesn't have a tempstat. thanks for the replys guys much appreciated

Answer 1

Hi mate, to start with don't panic and look at the simple things first.
If you have a manual it will pay dividends even after you fix this problem!
A manual will give you the correct thermostat opening temperatures and maximum opening temperature as well as the amount of lift your thermostat will open.

O.K, so you have looked at coolant level. It's O.K! Move on to the next level.
Look at your radiator. Your cooling fins on your radiator should be staright and have no major bent fins that block airflow. If this happens obviously the airflow will not pass through the core allowing a heat exchange to take place.
Use a small flat blade screw driver and carefully straighten them out. If the rad is dirty, use some mild pressure from your garden hose and lightly blast it from the engine side of your rad to clean it. Don't try to force it through the way the airflows through it otherwise you may just force the debris in further.
Following this,
look at the cooling circuit. If you have clean coolant in your engine, drain it out completely into a clean bucket and locate your thermostat housing. Remove your thermostat.

Leave the lowest hose drain off from where you drained your coolant.
Use the good old garden hose again and flush the circuit in through the drain hose, observe for any debris and major discolouration.
I would also suggest removing the hoses from your rad and flush from one side to the other, there shouldn't be any restriction when you do or otherwise there is a lot of crap in there. If so, I would suggest removing the rad from your machine for the next step.You may need to buy some hydrochloric acid. Water it down, say 6 to 1 and bung the lower half of the rad and fill it.
Be very observant so you don't end up up with nothing.
Time it! Keep it in there for say two minutes and drain into a clean bucket looking for debris.
If you are getting crap out of it you are winning. If not keep it in there a little longer and repeat the flushing cycle.
When you are happy it is clean, give it a good rinse in order to remove any of the acid.
So you have looked at your whole cooling circuit and it is O.K! One other thing is your Fan, but going from what you said I wouldn't expect it to be that due to the fact that you weren't stationary for too long, but it is peace of mind that will keep you fom being paranoid in the long run!
If you turn on your bike accesories but don't start it and remove your fan lead from your fan.
There should two leads from memory one relies on being ground from when the temp reaches its point at which the fan should kick in. If you ground this lead it should turn on.
If so you know it works. If not you need to trace it back to the thermostat housing which I 'am sure most bikes have their fan lead. This is where it gets it's signal to turn on.
You may need some hot water to test this and it is as simple as placing the end in the water at your required temp.
If all of that works, you need to try your thermostat in hot water.
Place a bit of wire through it and put some water in a saucepan. Suspend it in the water using the wire so it doesn't touch the sides. You will need a temp gauge and some pen and paper to record when it partially openes and when it is fully open. You should also record the lift the thermostat openes as this will hinder your cooling erformance if it doesn't open enough.
If nothing happens at all buy a new one and replace it!
Don't ever, not ride without one in it, any engine will look like it's running cool but that is a school boy error!
What happens is the coolant is passing through your engine too quickly to absorb the heat generated by the combustion therefore not cooling the engine properly.
The opposite is if the thermostat doesn't open at all, and the static coolant absorbs the engine heat to the point where it cannot escape, which is where your thermostat comes into play and opens when it feels the heat transfered through conduction. Coolant will gradually start to move through the circuit.
Once the engines is at temp the thermostat will often hover between fully open and partially open to regulate temperature in the engine. The radiator exchanges the heat when cool air passes through.
The last thing I would suggest is using 100% glycol coolant because it has better heat absorbing properties, so if you are unsure your machine doesn't have 100% bin it and buy some new stuff!

Good luck, Troy

Answer 2

That bike was never available in the US. This is the first time I've ever seen one. Cool looking bike!
It might be normal on that bike.
If it got hot enough to the point of overheating, the relief valve of the radiator cap would open and the coolant would blow out.
Does the fan come on?
Maybe the fan switch is bad.
If it never comes on -
Locate the switch (it's on the radiator).
With the key on, touch that wire to ground and the fan should come on.
For more fan tests, either ask some more questions, or purchase a shop manual.
http://www.motocom.com/motorcycles/

Answer 3

could be a bad thermostat or the viscosity of the coolant.
Try changing the coolant completely to a new tank of coolant, if that doesn;t work it's your thermostat.

Answer 4

You may want to check your hoses to make sure you don't have a clog in the line. Also, check the radiator for any leaks. Also, may need servicing. If internal parts aren't lubed properly, that will increase engine temp.

Answer 5

numerous reasons: Friction in the bearings Resistive heating in the windings Eddy contemporary losses in the steel. because of the fact the dynamo is made out of steel most of the flexibility from the rotating magnet produces contemporary in the steel shape as a substitute of the windings. IMHO that's in all probability the main important warmth source in a top designed and maintained dynamo

Answer 6

i would go with thermostat, maybe and this is a maybe a coolant temp sensor?

Answer 7

probably a bad thermostat